At Death’s Door: Hempel’s years in Brussels

On Monday 20 July 1936 at approximately 10 p.m. the intellectual and disciplinary identity of philosophy of science lay in the balance. Carl Gustav Hempel, commonly addressed as Peter, was dying. As his wife, Eva, stood idly and dumbstruck beside his bed, he was coughing blood. Their evening had begun with a different promise. After a week of intense labour, Peter had made the final improvements on an overdue manuscript. To relax and celebrate the finished work, Peter and Eva decided to join a friend, Ketelaer, on a bike ride to the Ter Kameren Bos (a major park of Brussels) and enjoy a well deserved summer picnic. “It was all so lovely”, Eva recalled the beginning of the evening in a later letter. At the time, Eva and Peter lived in a small, but comfortable apartment in the rue Timmermans, located on a hillside, overlooking the park of Vorst and the industrial neighborhood of Anderlecht in the distance. While cruising down with their bikes from their appartement in Vorst to Ter Kameren Bos along rows of the magnificent Art Nouveau villas of upper Ukkel, the dying glare of the summer sun signaled the long sought arrival of a holiday long overdue.

Peter and Eva's view from their apartment in Vorst.

For the last two months and by extension even the last three years, Peter had worked relentlessly to improve his professional reputation as a scientific philosopher. At the end of June, Peter and Eva had joined Peter’s employer and benefactor, Paul Oppenheim, to the second conference on the Unity of Science in Copenhagen - a gathering aimed at uniting philosophers and scientists from all over the world to reflect on the state of science, its division into subdisciplines, its ruptured conceptual apparatus and its significance for the future of society and international relations. From the contacts that Peter entertained during such gathering might come an opportunity for proper employment - unlike Peter’s current situation. Although Peter held a doctorate in philosophy from the prestigious Humbolt University of Berlin, he had no proper academic job. After Hitler had risen to power in March 1933, Peter’s supervisor, Hans Reichenbach, at the time philosophy professor at the university of Berlin, decided to migrate to Istanbul and accept a job there as professor, because impending racial laws would exclude him from performing his job in Berlin. As a result, Peter was left to his own devices. Thanks to the help of the psychologist Wolfgang Köhler and the philosopher Nicolai Hartmann, Peter was still able to pass the doctoral exam in March 1934, but found himself in a country where every one interested in his intellectual field, scientific philosophy, was either exiled to a foreign country or expelled from academia. Peter’s hope for an academic career within Germany was lost and, given his unwillingness to accept the political reality in Germany, he had no desire to become a Gymnasium teacher. In order to help his most promising former student, Reichenbach tried to hire Peter as an assistent in Istanbul, but quickly found out that his Turkish employers had no intention to offer a position to every German who sought escape from the clutches of Nazi rule. In this hour of desperation, Reichenbach contacted his richest acquaintance to help Peter out.

This acquaintance was Paul Oppenheim - a trained chemist, an ardent enthousiast of the new, but now exiled, German scientific philosophy and a very rich man who enjoyed all the leisurely benefits of his Jewish family’s business in precious gems. Oppenheim was married to Gabrielle Errera, herself born into a rich Jewish family from Brussels. Before racial laws were implemented in Germany, the Oppenheims had already moved to Gabrielle’s native Brussels where they lived in a modern villa, surrounded by a wonderful garden, on one of the richest streets of Brussels, the Avenue Victoria. Oppenheim sympathized with Peter’s situation and decided to hire him as his research assistant. Oppenheim had acquired a personal interest in the logic of concept formation and for his leisure during his exile from his home country he wanted to investigate the logical status of type-concepts in modern psychology. Since Oppenheim was never trained in formal logic, Peter would function as his co-worker to guide his ideas. In September 1934, Eva and Hempel moved to Brussels thanks to the labour contract that Oppenheim provided.


By July 1936 Peter and Oppenheim had already finished their first book, The Type Concept in Light of the New Logic (Der Typusbegriff im Lichte der neuen Logik). Because Oppenheim was so pleased with Peter’s work and his intellectual company, Oppenheim decided to support Peter until he had secured an academic position abroad. However, this was no easy task: Peter was but one of a swarm of German intellectuals looking for employment, and unlike many others, he had virtually no teaching experience or published work to boast. Despite his attempts to engage the local philosophers in a lecture at the University of Brussels, Peter’s chances to find work in Belgium were slim. The Brussels logician Marcel Barzin and his young pupil Chaïm Perelman were interested to learn about German scientific philosophy, but had no intention of hiring him. In a letter to Reichenbach, Peter remarked that the Belgians in general were ill-disposed towards Peter and Eva. They had quickly acquired French, but their German accents betrayed their country of origin. Peter felt that he could not blame the Belgians for their attitude, given the way the Germans had invaded Belgium during the Great War. Reichenbach suggested Peter to turn his professional gaze towards the United States. To acquire a job there, Peter needed contacts and some English publications in American journals. The manuscript that Peter had finished on 20 July 1936 was most likely “A Purely Topological Form of Non-Aristotelian Logic”, written for The Journal of Symbolic Logic, exactly what he needed to further his career.


As any academic knowns, the experience of joy upon the completion of a manuscript is hard to grasp and lasts only a brief moment. Just before the direction of Peter’s fortune was about to reverse, he was riding down the streets of Ukkel enjoying that shallow window in time when one can feel the happiness of accomplishment . He had only recently learned to ride a bike. Perhaps his enthusiasm made him overconfident. On a steep street downhill, the path unexpectedly changed its direction from left to right and Peter had to manoeuvre across the street at great speed. A large, metal sign post blocked his path which he was unable to dodge. The impact was immense, thrusting him on the ground head forward. Trapped under his bike, he lay unconscious. With the help of their friend Ketelaer, Eva dragged Peter to the nearest house and gently lay him on a table. His nose and ears were bleeding. Initially, Eva did not think the worst. He only had a massive bump on the head.


Although it is impossible to ascertain where exactly the accident occurred, the entrance to the Ter Kameren Bos from the Bospleinlaan is most likely. The Bospleinlaan is a steep road of cobble stones - a challenge for every beginning biker, and in order to enter the park from that street one has to change direction from left to right. Even today that entrance of the park is marked by big iron sign posts around which one has to manoeuvre. The stones cannot tell us, but most likely here the history of philosophy of science could have taken a different turn.

Peter came down the Bospleinlaan at great speed to enter Ter Kameren Bos.
In order to enter the park, Peter had to change directions. A huge metal signpost blocked his path.

After some time, an ambulance arrived and Peter was transported to the nearest hospital - most likely the public and catholic hospital Saint-Elisabeth. The doctor on watch quickly diagnosed Peter’s fractured skull. The situation was critical. To her bewilderment, Eva was asked whether a catholic or a protestant priest should be called. The nuns said that nothing could be done and prepared Eva for the worst. The director of the hospital was alerted of the situation and explained, to Eva’s horror, that she would soon have to leave Peter behind. Since it was a public, catholic hospital, Peter could not be given a private room and she was not allowed to stay with him overnight. There was an option to go to a private hospital, but any further transportation of Peter was extremely dangerous. The director advised her to go home and promised that she would receive a telephone call if Peter’s situation changed during the night. Fortunately for her, Paul Oppenheim appeared in the general hospital room just as she was gently forced out. This sudden appearance of an Errera family member changed the desperate situation for the German couple who’s joyous summer evening had turned into a heartbreaking calamity. Oppenheim secured Hempel a private room and insisted that a senior surgeon would be sent for. When the surgeon arrived, Peter’s situation had already worsened significantly. His breathing was impaired and the nurses told Eva that Peter was going to die. The surgeon decided to give Peter two injections of adrenaline and tapped off spinal fluid which was saturated with blood from his brain. Afterwards, Peter could breath again and his situation stabilized. Eva left the hospital at midnight and was accompanied by Oppenheim to his villa. Every moment of that long night she lay awake waiting for the telephone to ring, hoping that it never would. In the morning, the hospital called the Oppenheims with good news: Peter had vomited all the blood in his stomach overnight and had regained his full consciousness with the early rising of the summer sun.


Peter Hempel lived. Paul Oppenheim would support his intellectual work for two more years, until Peter left for the United States in January 1939 to begin an American adventure that would change him, his philosophy and eventually the self-understanding of philosophers of science forever.


You can pick up the rest of Hempel's story and the way he changed philosophy of science forever in my new paper (to appear in Philosophy of Science) "Beyond Hempel: Reframing the Debate about Scientific Explanation". A pre-print version can be found here: http://philsci-archive.pitt.edu/id/eprint/19324


The above story is mostly based on two letters:


- Eva Hempel to Ina Carnap, 22 July 1936 , Rudolf Carnap Papers, 102-14-15 - a captivating and beautifully composed letter written from Oppenheim's villa in the Avenue Victoria.

- Carl Hempel to Hans Reichenbach, 7 November 1936, Hans Reichenbach Papers, 13-46-09 - the first letter from Hempel to Reichenbach after the accident, containing a particular reference to Oppenheim's crucial intervention at the hospital.


The story was also (briefly) told by Oppenheim in:


- 1969, "Reminiscences of Peter", In: Essays in Honour of Carl G. Hempel, Rescher, N. (ed), Dordrecht: Springer


I wish to thank Jan Potters for finding the most likely location of Hempel's accident and for joining me on an amazing Hempel-tour through Brussels.